Field
Implementations described herein generally relate to semiconductor manufacturing and more particularly to a device and method for controlling a profile of a plasma in the semiconductor chamber.
Description of the Related Art
As the feature size of the device patterns get smaller and smaller, the critical dimension (CD) requirements for these features become a more important criteria for obtaining stable and repeatable device performance. Maintaining surface uniformity for a substrate, in which the features are formed in, facilitates achieving the critical dimensions for these features. In plasma processing, surface uniformity for a layer of the substrate deposited and/or etched is challenging due to the non-homogeneous profile of the plasma processing the substrate. The non-homogeneous profile of the plasma may be due to chamber asymmetries such as chamber and substrate temperature, flow conductance, chamber pumping and non-uniform RF fields, among other factors.
Achieving the allowable variations in the CD across a substrate is difficult when processed by a plasma reactor due to the non-homogeneous profile of the plasma. For example, some regions of the plasma may have greater concentration of reactive ions and result in greater etch or deposition rates for the substrate in that region while other regions may be starved of reactive ions, i.e., has a lower density, resulting in lower etch or deposition rates. Thus, the non-homogeneous plasma profile leads to non-uniformity in the surface of the substrate resulting in CD which may become out of specification.
Thus, there is a need for improving the uniformity of the surface for a substrate undergoing plasma processing.